Bosch Therm C950ES Technical Service Bulletin

Technical Service Bulletin:
Replacing & Servicing The Condensing
Heat Exchanger
Models: C950ES, C1050ES
Introduction
If replacing the copper heat exchanger (below the condensing

heat exchanger), refer to Technical Service Bulletin: Replacing
the Copper Heat Exchanger once the condensing exchanger has
been removed.
Tools needed:
Phillips head screwdriver

8mm nut driver with 6" extension

4mm allen wrench

Clean rag

Preparation
1. Unplug water heater and turn off gas to heater using installer
supplied manual shut off valve.
2. Remove front cover and combustion cover using instructions in
the installation manual.
3. Close installer supplied inlet isolation or shut off valve and open
a hot water tap to release pressure and drain. If water fl ows
continuously from the tap, a plumbing crossover is present and
must be corrected.
4. Disconnect inlet and outlet piping from the water heater to
facilitate draining. Have a bucket ready to catch water.
5. Place a clean rag over the water heater's control unit to catch any
residual water when removing pipe connections.
Removing the condensing heat exchanger
1. Remove Phillips head screw, gasket and exhaust temperature
sensor from center of condensing exchanger. (Fig. 1, pos. 1).
2. Remove overheat sensor/ECO wires from sensor on heat
exchanger. (Fig. 1, pos. 2). Ensure that wires are out of the way
for heat exchanger removal and reinstallation.
3. Remove clip from black condensate drain pipe connection and
pull drain pipe free. (Fig. 1, pos. 3).
4. Remove clips on copper pipe connecting upper and lower heat
exchanger and remove pipe (Fig. 2, pos. 1). Dripping water is
likely.
5. Remove clips from top and bottom of cold water pipe and
remove pipe from heater (Fig. 2, pos. 2). Dripping water is likely.
6. Remove the two Phillips screws and two 4mm hex head screws
from the top left and right of the exchanger (Fig. 2, pos. 3).
7. Remove the four 8mm nuts from the bottom front and top rear of
condensing exchanger. (Fig. 2, pos. 4). Note: two left nuts are
not visible in Figure 2.
8. Remove the condensing heat exchanger by pulling it forward and
out of the heater.
Figure 1